Adapalene is the International Nonproprietary name (INN) of an pharmaceutical ingredient, the chemical name of which is 6-[3-(1-adamantyl)-4-methoxyphenyl]-2-naphtoic acid, and which has the formula (Ia):

Adapalene is an antiacne agent, derived from naphthoic acid, with antiinflammatory and keratolityc properties.
Patent application EP 199.636-A1 describes benzonaphthalenic derivatives and their therapeutic and cosmetic utility. It is also describes a process for their preparation. Among the compounds described are several 1-adamantane derivatives, such as Adapalene, which is obtained by transforming the 2-(adamantyl)-4-halogen anisol into its magnesium, lithium or zinc derivative, followed by coupling with methyl 6-bromo-2-naphthoate and subsequent hydrolysis of the obtained ester in basic conditions. This process presents the drawback that the halogenated derivatives of the methyl naphthoate are difficult to prepare and are obtained with low yields.
On the other hand, patent application WO 01/56563-A1 describes several aromatic derivatives of 1-adamantane, including Adapalene and its use for the treatment and/or prevention of cancer.
Therefore, from what is known in the state of the art, it is derived that the provision of an alternative process for the preparation of aromatic derivatives of 1-adamantane which is efficient and of easy industrialization, would be of great interest for the industrial preparation of these compounds.